Fan arrangement



W E T ZN9 Lml UEl,

C Re amm un F Feb. 6, 1968 INVENTOR JAMES L.. SCHULZE BY w.

naz

FIGLI FIGB United States Patent Office 3,367,566 FAN ARRANGEMENT James L. Schulze, Middletown, Ky., assigner to General Electric Company, a corporation of New York Filed Dec. 1, 1965, Ser. No. 510,831 4 Claims. (Cl. 230-120) ABSTRACT F THE DISCLOSURE A fan arrangement compising an axial flow propeller fan and a generally rectangular inlet chamber including a front wall having a fan orifice surrounding the fan. The chamber includes an air inlet at one end so that air flows into the fan in a direction parallel to the blades. A baille extending from one side wall of the chamber to a point overlapping the ends of the blades prevents reverse ow of air through the inlet.

The present invention relates to propeller fans and is more particularly concerned with an improved air flow arrangement including a propeller fan as the air moving means.

The conventional axial ow propeller fan delivers the maximum volume of air when no appreciable static pressure condition is involved, that is, whenit is operating as a free air fan with the principal air flow to and from the fan along an unrestricted path generally parallel to the axis of rotation of the fan. However, in some applications of a propellerfan as for example in room air conditioners, space limitations necessitate an air flow arrangement such that the inlet air iiows to the fan along a radial path, that is, along a path normal to, rather than parallel to the fan axis. Under such conditions, the volume of air circulated by a given'fan is less than its rated capacity as a free air fan. It has been found that much of this decrease is due to the fact that .the rotating fan blades set up a rotating air current upstream from the fan orifice having a tangential ow component which, when acting in the direction of the air inlet, interferes .with or in other words opposes the free ow of incoming air to the fan.

The present invention is concerned with and has as its principal -object the provision of an improved propeller fan air flow arrangement including an air-inlet to one sfide of the fan and'm'eans for preventing the rotating air current set up by the fan from interfering with or opposing the ow of incoming air whereby there is obtained a significant increase inthe volume of air circulated by the fan.

Further objects and advantages of the invention will become apparent from the following description and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

In accordance with the illustrated embodiment of the invention, there is provided an air flow arrangement comprising an axial flow propeller fan and walls dening an air inlet chamber for the fan including an air inlet to one side of the fan such that at least a major portion of the incoming air flows along a path which is at a right angle to the axis of rotation of the fan or parallel to the plane of the fan blades. In order to prevent the rotating air pattern set up by the fan from interfering with or opposing the tiow of incoming air to the chamber, means are provided on the side wall of the chamber along which most of the opposing -or reverse air ilow takes place, for deecting this interfering air ow into and through the fan.

For a better understanding of the present invention reference may be had to the accompanying drawing in which:

FIGURE 1 is a plan view, partly in section, of a room 3,367,566 Patented Feb. 6, 1968 air conditioner incorporating the air flow arrangement of the present invention;

FIGURE 2 is a sectional View taken generally along line 2 2 of FIGURE 1; and

FIGURE 3 is a sectional View taken line 3 3 of FIGURE 1.

Referring particularly to FIGURE 1 of the drawing, there is shown therein the application of the present invention to a room air conditioner which comprises a casing 1 divided by a partition 2 into an indoor compartment 3 and an outdoor compartment 4. The air conditioner also includes a refrigeration system comprising a compressor 5 and a condenser 6 positioned in the outdoor compartment 4 and an evaporator 7 positioned in the indoor compartment 3. For purpose of circulating indoor air over the evaporator 7 and outdoor air over the condenser 6, there is provided air moving means in the form of a blower 9 within the indoor compartment and a multiple blade propeller type fan 10 in the outdoor compartment both of which are driven by means of a motor 11 positioned in the outdoor compartment 4.

The air flow path for the circulation of outdoor air through the outdoor compartment is formed by means including a second partition or housing 12 spaced from partition 2 and having a fan orifice 14 therein in which the fan 10 is positioned. Outdoor air is drawn into the compartment 4 through an inlet grille 15 and after flowing in heat exchange relationship with the compressor 5, motor 11 and condenser 6 is discharged through outlet grille 17.

By this arrangement, it will be seen that the portion 19 of the partition 12 including the fan orifice 14 forms the front wall of a generally rectangular inlet chamber 20 behind or upstream from the fan 10. This chamber 20 is further dened by the adjacent portion of the partition 2 which forms the back wall thereof and by portions of the casing which form the top side wall 22, the vertical end wall 23 Vand the bottom side wall 24 of the chamber 20. Air ows into the chamber 20 through the open end 25 thereof to the right of the fan as viewed in FIGURE l, which inlet is defined by the adjacent portions of the partitions 2 and 12 and the walls 22 and 24.

During operation of the fan 10, air drawn inwardly through the air inlet 25 iiows to the fan along a path generally perpendicular to the axis of rotation of the fan represented by drive shaft 26. With 'this type of generally radial tiow of inlet air to the fan 10, a portion thereof is continuously picked up by the tips of the fan blades and circulated in an annular path on the upstream side of the orice 14. Specically `and assuming a counterclockwise rotation of the fan, this circulating air current rotates along an annular path indicated by the dotted arrows in FIGURE 2. Centrifugal forces in this rotating air stream also tend to deflect this air ow tangentially from the periphery of the fan. This tangential movement of the circulating air portion is restricted on three sides of the fan by the walls 22, 23 and 24. However, in the area of the inlet 25 where there is no confining wall, the circulat-` ing air stream is free to ow in the direction of the inlet 25 in a counterflow direction with respect to the incoming air. This counterflow of air opposes or interferes with the free flow of air into the chamber 20 thereby decreasing the air iiow rate through the compartment.

In accordance with the present invention, means are provided for shearing the rotating air from the blade tips and deecting it into and through the fan orifice at a point such that there is at the most a neglible counterow of air towards inlet 25. More speciically, there is provided a baffle 28 extending upwardly from the wall 24 forming the side of the chamber 20 along which the objectionable counterflow takes place. In other words, this baffle 28 is directly in the tangential path of that portion of the air generally along which would otherwise reverse ilow towards the inlet 25. More specifically, it has been found that in the illustrated embodiment the baille 28 operates best when it is positioned immediately below the axis of rotation of the fan as represented by the shaft 26. Stated more broadly, the baille 28 and fan axis 26 should preferably be in substantially the same plane, which plane is generally perpendicular to the ilow path of the air entering through the inlet 25 with the baille 28 positioned within the chamber 20 at a point offset approximately 90 in a direction opposite to the direction of rotation of the fan 10 from the line of ilow of the air stream entering the inlet 25. However, some improvement in air ilow may be obtained by positioning the baille a few degrees, as for example about up to 10 to 15, to one side or the other of the illustrated position.

For best results, the baille 28 should be in contact with the wall 24 and should extend outwardly therefrom or, in other words, in the direction of the fan 10 to a point where it overlaps at least the extreme of the blade length. However, wider baffles which provide a greater overlapping of the blade area may be used as they do not appear to significantly affect the improved results obtained by a baille overlapping about 5% of the blade length.

For best results, the baille 28 should also be curved or positioned at an angle between the wall 2 and the wall 19 in order to facilitate deflection of the rotating air stream into and through the fan orifice 21. An angle of about 45 is preferred.

Extensive test results have indicated that the presence of the baille 28 significantly increases the total c.f.m. delivered by a fan arrangement of this type. For example, in a room air conditioner in which the average air ilow using a propeller type fan was about 200 c.f.m. and all of the incoming air entered through one side of the inlet chamber, the addition of the baille 28 overlapping the tips of the blades by about 5% of the length thereof and extending to a point within about one-eighth inch of the inlet edge of the blades increased the air ilow by approximately 100 cfm. In other words, the baille provided a 50% increase in the air ilow rate. Another test involved a construction in which about one-third of the incoming air entered the chamber 20 through leakage paths around the housing 12 specifically above the chamber and in the side opposite inlet as indicated by numerals 31 and 32 respectively, and the remaining twothirds through inlet 25. Significant improvements were also obtained in this construction by use of the baille 28. Speciilcally, the presence of the baille increased the air ilow rate from about 450 c.f.m. to 490 cfm., or, in other words, by about 10 percent.

While there has been shown and described a particular embodiment of the present invention it will be understood that it is not limited thereto and is intended by the appended claims to cover all such modiilcations as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An air ilow arrangement comprising an axial ilow propeller fan having a plurality of blades,

a generally rectangular inlet chamber including a front wall having an annular orifice therein surrounding said fan, a rear wall spaced from said front wall and opposed side walls spaced from the periphery of said fan,

one end of said chamber being open to provide an air inlet to said chamber whereby most of the incoming air ilows to said fan in a direction generally parallel to the plane of said blades and whereby a portion of the incoming air tends to rotate with the blades and' to be tangentially discharged therefrom and reverse ilow along one of said side walls in the direction of said air inlet,

and means for substantially preventing such reverse ilow comprising a baille extending from said side wall to a point overlapping the outer ends of said blades and from said front wall to said back wall.

2. The air ilow arrangement of claim 1 in which said baille overlaps at least 5% of the lengths of said blades.

3. The air ilow arrangement of claim 1 in which the baille is substantially in a plane including the axis of rotation of said fan and substantially perpendicular to the direction of air ilow into said chamber from said inlet.

4. The air ilow arrangement of claim 1 in which said baille extends at about a angle from said back wall to said front wall.

References Cited UNITED STATES PATENTS 1,693,352 11/1928 Schmidt 103-111 2,325,154 7/1943 Walters 230-120 2,737,897 3/1956 Dewees 103-111 FOREIGN PATENTS 1,283,759 12/1961 France.

1,052,624 3/1959 Germany.

HENRY F. RADUAZO, Prnuzry Examiner. 

